In addition to the refrigerating chamber and the freezing chamber separated from each other, the refrigerator is provided with a so called machine room in a lower part thereof, and air passages in a rear part of the refrigerating chamber and the freezing chamber connected thereto. The heat exchanger (evaporator) is fitted on the air passages, together with a fan, for supplying cold air to the refrigerating chamber and the freezing chamber in association with a compressor and condensers in the machine room. That is, high temperature and high pressure refrigerant supplied through the compressor and the condensers is evaporated in the heat exchanger, to cool down environmental air by a latent heat of the vaporization. The fan circulates air throughout the Refrigerator for supplying the air cooled down through the heat exchanger to the refrigerating chamber and the freezing chamber, continuously.
A related art heat exchanger for the refrigerator is illustrated in FIGS. 1 and 2, referring to which the related art heat exchanger will be explained.
As shown, the heat exchanger is provided with refrigerating tube 1 for flow of the refrigerant, and a plurality of fins 1 fitted at fixed intervals parallel to one another along the refrigerating tube.
In more detail, the refrigerating tube 1 is coupled with the fins 2 while one line of the refrigerating tube 1 forms one column in the heat exchanger. FIG. 2 illustrates two columns formed by two lines of refrigerating tube 1.
As shown in FIG. 2, the fin 2, actually in a form of small plate, has through holes 2a for coupling with the refrigerating tube 1. That is, the related art heat exchanger has discrete fins 2, to form discrete heat exchange surfaces along a length of the heat exchanger.
Moreover, during operation, much moisture in the air in the refrigerator is frosted on surfaces of the heat exchanger owing to a subzero environmental temperature, to impede circulation of the air. Therefore, in general, there is defroster 3 provided to the heat exchanger for defrosting, for which separate defrosting process is conducted.
The heat exchanger stands upright in the air flow passage, and the air in the refrigerator is introduced into the heat exchanger from below and exits from a top of the heat exchanger as shown in arrows.
Currently, despite the foregoing heat exchangers are applied to most of the refrigerators, the heat exchangers have the following structural problems, actually.
For an example, the fins 2 are fitted to the refrigerating tube 1 one by one because the fins 2 are discrete and have individual shape characteristics. The fins 2 are fitted along the refrigerating tube at intervals different from each other between an upper part and a lower part thereof. That is, as a flow resistance caused by the growth of the frost deteriorates a heat exchanger performance, the fins 2 are fitted in the lower part, an air inlet side, that has more frosting at intervals greater than the upper part.
Water from the defrosting stays at lower edges 2b of the fins 2 in a form of a relatively big water drop by surface tension, and acts as nuclei of frost growth in a subsequent operation of the refrigerator (cooling process), again. Therefore, in order to suppress the growth of the frost, as shown, it is required that the defroster 3 is arranged so as to be in contact with every lower edge 2a. 
At the end, the use of the discrete type of fins makes a structure of the related art heat exchanger complicate actually, that makes assembly difficult. Moreover, it is preferable that the heat exchanger is small sized and has a high efficiency because the heat exchanger is placed in the comparatively small air flow passage. However, the foregoing structural problem impedes design change of the related art heat exchanger, for optimization of the heat exchanger.